Hong Young Jun, Kang Yun Chan
Department of Materials Science and Engineering, Korea University, Anam-Dong, Seongbuk-Gu Seoul 136-713, Republic of Korea.
Nanoscale. 2015 Jan 14;7(2):701-7. doi: 10.1039/c4nr05373g.
Core-shell structured Zn2SnO4-carbon microspheres with different carbon contents are prepared by one-pot spray pyrolysis without any further heating process. A Zn2SnO4-carbon composite microsphere is prepared from one droplet containing Zn and Sn salts and polyvinylpyrrolidone (PVP). Melted PVP moves to the outside of the composite microsphere during the drying stage of the droplet. In addition, melting of the phase separated metal salts forms the dense core. Carbonization of the phase separated PVP forms the textured and porous thick carbon shell. The discharge capacities of the core-shell structured Zn2SnO4-carbon microspheres for the 2(nd) and 120(th) cycles at a current density of 1 A g(-1) are 864 and 770 mA h g(-1), respectively. However, the discharge capacities of the bare Zn2SnO4 microspheres prepared by the same process without PVP for the 2(nd) and 120(th) cycles are 1106 and 81 mA h g(-1), respectively. The stable and reversible discharge capacities of the Zn2SnO4-carbon composite microspheres prepared from the spray solution with 15 g PVP decrease from 894 to 528 mA h g(-1) as current density increases from 0.5 to 5 A g(-1).
通过一锅喷雾热解法制备了具有不同碳含量的核壳结构Zn2SnO4-碳微球，无需任何进一步的加热过程。由含有锌盐、锡盐和聚乙烯吡咯烷酮（PVP）的一个液滴制备出Zn2SnO4-碳复合微球。在液滴干燥阶段，熔融的PVP迁移到复合微球的外部。此外，相分离金属盐的熔化形成致密的核。相分离的PVP碳化形成有纹理的多孔厚碳壳。在1 A g(-1)的电流密度下，核壳结构的Zn2SnO4-碳微球在第2次和第120次循环时的放电容量分别为864和770 mA h g(-1)。然而，通过相同工艺制备的不含PVP的裸露Zn2SnO4微球在第2次和第120次循环时的放电容量分别为1106和81 mA h g(-1)。当电流密度从0.5 A g(-1)增加到5 A g(-1)时，由含有15 g PVP的喷雾溶液制备的Zn2SnO4-碳复合微球的稳定且可逆的放电容量从894 mA h g(-1)降至528 mA h g(-1)。
